As a scroll compressor whose compressor capacity can be increased without increasing the outside diameter of a scroll member, a scroll compressor has been proposed in which a top surface and a bottom surface of spiral wraps of a fixed scroll member and an orbiting scroll member, forming a pair, are each provided with a step portion, the wrap height of the spiral wraps on the outer peripheral side of the step portions is made higher than the wrap height on the inner peripheral side, so as to enable three-dimensional compression in a circumferential direction and a height direction of the spiral wraps. Because this compressor is capable of compression not only in the circumferential direction of the spiral wraps but also in the wrap height direction, it is possible to increase the displacement and increase the compressor capacity compared with a typical scroll compressor (two-dimensional compression) having no step portion, as described above. Accordingly, compared with a compressor having the same capacity, there are advantages in that, among others, it is possible to reduce the size and weight.
Patent Document 1 discloses that, in a scroll compressor capable of three-dimensional compression, as described above, the top surfaces on the outer peripheral side and on the inner peripheral side of the step portion of the spiral wrap are each provided with a tip seal, and a tip seal groove on the outer peripheral side is provided with an introduction path through which internal pressure in a high-pressure compression chamber on the center side is introduced, whereby the sealing function of the tip seal on the outer peripheral side is enhanced to reduce the amount of gas leakage from the top surface of the wrap on the outer peripheral side of the step portion of the spiral wrap and to improve the compression efficiency.
Patent Document 2 discloses that, in a scroll compressor having a typical structure in which the top surface and the bottom surface of the spiral wrap are not provided with the step portion as mentioned above, a back-pressure guide portion formed by thinning the seal end or by deepening the seal groove end is provided at the spiral starting end of the tip seal or the tip seal groove. By making the back-pressure guide portion flexurally deform, thermal expansion deformation is absorbed, thus obtaining uniform sealing properties of the tip seal and preventing abnormal abrasion, which improves the durability and the reliability.    Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2002-138975    Patent Document 2: Japanese Unexamined Patent Application, Publication No. Hei 4-255588